1. Field Of The Invention
This invention relates to a valve which shuts off the flow of a liquid while reducing the noise caused by the shut-off. It appears especially well suited for use in the plumbing field.
2. Description Of The Art
When a valve shuts off the flow of a fluid, a sudden drop of pressure can occur behind the outflowing fluid. Sometimes the reduced pressure is below the vapor pressure of the fluid, thereby creating bubbles in it. As the system rapidly returns to pressure equilibrium, the bubbles collapse. This is known as cavitation and can cause noise and vibration which, in addition to being unpleasant, can damage components and disrupt the proper functioning of the system.
Cavitation is a special problem in diverter valves which receive fluid from one or more intake conduits and selectively direct the flow to one or more of a plurality of output conduits. One such valve is used to enable a bather to direct the water supply through a tub spout or a shower head. In many such diverter valves, one quick stroke of a valve member can almost instantly block a currently flowing outlet and open another. The suddenness of this action causes significant cavitation effects. In some cases the effect is so pronounced that the valve bounces off the desired position so as to defeat the selection.
Another factor complicating efforts to solve this problem is that plumbing codes regulate how air can be let into lines (e.g., in the case of a vacuum breaker). When air is let into a line from an opening below or behind a deck, the risks of water damage due to leakage is greater. Further, codes require accessibility of such structures.